Homebrew_PCBs

When I made boards back in the late 70's I used ammonium persulfate
most of the time. Works good, no stains.
I have no idea if it's still readily available or where to get it.


Steve


------------------------------------------------------------
At 06:56 PM 7/2/2017, you wrote:

>I have been using ferric to etch boards for a while now. Recently I
>got lucky and came into a cache of 1973 vintage copper clad PCB
>stock, which will enable me to make some reproduction pieces that
>are pretty much indistinguishable from originals in terms of
>look. However, I have noticed that the ferric solution stains these
>boards, adding a yellowish tint. Is there any way to avoid
>this? Or clean it after?

Hi

Sorta new here and trying to catch on to some of the procedures described
here.

Was wondering if anyone knows if theres a chemical or chemicals (s) that
will safely dissolve epoxy that some manufacturers
use to encapsulate boards to protect them and make them more or less
unservicable when a component fails?

I have hears there is a chemical that they can be soaked in for many days,
and you have to check on it daily before it eats through
things that u dont want it to damage.

Steve Hearns
Technotronic Dimensions [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM
1.518.663.3421 (MAIN)
1-877-817-9885 (Voice / Fax Toll Free - US Only)
E-Mail: Steve@...
--
Webmaster, Parts-Link: (http://www.parts-link.com)
Group Moderator:
TV-Repair (http://groups.yahoo.com/group/tv-repair)
Monitor-Repair (http://groups.yahoo.com/group/monitor-repair)

----- Original Message -----
From: "LEON HELLER leon355@... [Homebrew_PCBs]"
<Homebrew_PCBs@yahoogroups.com>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, July 03, 2017 12:56 AM
Subject: Re: [Homebrew_PCBs] Ferric chloride staining PCB substrate


Oxalic acid removes ferric chloride stains. I've got a big bottle of it
somewhere but have never used it.
Leon

On Monday, 3 July 2017, 2:56, "'Brad' unclefalter@...
[Homebrew_PCBs]" <Homebrew_PCBs@yahoogroups.com> wrote:

Oxalic acid is also sold as, "wood bleach" usually findable in hardware or paint stores.

On 04/07/17 04:57, 'Technotronic~Dimensions'
infotech@... [Homebrew_PCBs] wrote:

> Hi
>
> Sorta new here and trying to catch on to some of the procedures described
> here.
>
> Was wondering if anyone knows if theres a chemical or chemicals (s) that
> will safely dissolve epoxy that some manufacturers
> use to encapsulate boards to protect them and make them more or less
> unservicable when a component fails?
>
> I have hears there is a chemical that they can be soaked in for many days,
> and you have to check on it daily before it eats through
> things that u dont want it to damage.

An easy way is to have a stream of hot air directed at the board (hot air gun on
a stand), and pick away at the epoxy with a thin sharp screwdriver and thin pliers.

Hot epoxy goes soft and rubbery.

Steve,

With regard to dissolving epoxy, I have good news, and I have bad news. The good news is that there are chemicals used for depotting encapsulated assemblies.

Back in the days before dirt was invented, I ran a failure analysis lab for my employer where my technicians used several chemicals from Dynaloy. They were sold under the Dynasolve product line. We also used another product of theirs called Decap. Here is a website for one of their distributors: http://www.ellsworthadhesives.ca/manufacturer/dynaloy

I note that they now have a greater variety of chemicals than were available "way back then."

That being said, there are a few issues (the bad news):

1. The chemicals don't dissolve the epoxy. They swell the epoxy and cause it to flake off. Active removal (scraping) is required

2. I think we had to match the chemical to the epoxy cure system, i.e. amine, phenol, etc., to get the best performance. I don't know if this is more or less so now, with the greater number of chemicals available  today.

3. Since the circuit boards are usually epoxy impregnated, they will suffer as a result of this treatment. Any other parts that are epoxy encapsulated, or made with certain plastics would likely be adversely affected.

4. To say that the chemicals were pricey, would be a gross understatement. We bought them by the gallon, and each gallon cost an arm, a leg, and someone's first born son.

The chemicals did the job for us because our usual need was to retrieve the failed components from the assembly. We had little concern for the assembly itself. The items we were after were in metal or ceramic packages, and therefore were not affected by the chemicals. Although the possibility of removing the epoxy and repairing an assembly exists, it is expensive and labor intensive, with a low probability of success.

On the very rare occasion that a module had to be repaired because there was no other choice, a different technique was used. This technique is not generally available outside a lab like ours, but I present it just in case you have access to the necessary machinery/information.

This technique requires good information on the construction of the module. We started by performing X-Ray in X, Y and Z axes. The X-Ray results were compared to the original assembly drawings, and the component of interest was located. By using extremely precise drilling and milling tools, combined with progressive X-Rays, a cavity was made around the part to be replaced. Every attempt was made to make the cavity very close to the part. The cavity was then filled with the chemical of choice, and the epoxy slowly scraped away, exposing the component. Just watching this process was painful. I don't even want to discuss how difficult it was to replace a component once the cavity was open and the defective component removed.  To underscore: this was only done when there was no possibility of getting a replacement module, or the time it would take to get a replacement would have a devastating impact on delivery schedule.

Harvey A

 

Hi

Sorta new here and trying to catch on to some of the procedures described
here.

Was wondering if anyone knows if theres a chemical or chemicals (s) that
will safely dissolve epoxy that some manufacturers
use to encapsulate boards to protect them and make them more or less
unservicable when a component fails?

I have hears there is a chemical that they can be soaked in for many days,
and you have to check on it daily before it eats through
things that u dont want it to damage.

Steve Hearns
Technotronic Dimensions [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM
1.518.663.3421 (MAIN)
1-877-817-9885 (Voice / Fax Toll Free - US Only)
E-Mail: Steve@...
--
Webmaster, Parts-Link: (http://www.parts-link.com)
Group Moderator:
TV-Repair (http://groups.yahoo.com/group/tv-repair)
Monitor-Repair (http://groups.yahoo.com/group/monitor-repair)

----- Original Message -----
From: "LEON HELLER leon355@... [Homebrew_PCBs]"
<Homebrew_PCBs@yahoogroups.com>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, July 03, 2017 12:56 AM
Subject: Re: [Homebrew_PCBs] Ferric chloride staining PCB substrate

Oxalic acid removes ferric chloride stains. I've got a big bottle of it
somewhere but have never used it.
Leon

On Monday, 3 July 2017, 2:56, "'Brad' unclefalter@...
[Homebrew_PCBs]" <Homebrew_PCBs@yahoogroups.com> wrote:

Hi Harvey

Great info, thanks. With more stuff out there being designed not to be
fixed, and thrown away, I had always wanted to
know more about the possibilities.

I remember when I worked in the Aerospace industry, the painter at our plant
carried MEK / Methyl Ethyl Keotene
around in ample supply, and some of that on a cloth woould pretty much take
the paint right off the surface of an
airplane no problem.

I remember it was not very pleasant at all to smell and it had a pretty high
hazmat rating sticker on it and he did not
leave that container open unless he was using it. He was suppose to wear a
respirator also if I remember right.

I got the impression that stuff would dissolve most anything even maybe
tough epoxy but never tried it.


Steve Hearns
Technotronic Dimensions, VT [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM
1.518.663.3421 (MAIN)
1-877-817-9885 (Voice / Fax Toll Free - US Only)
E-Mail: Steve@...
--
Webmaster, Parts-Link: (http://www.parts-link.com)
Group Moderator:
TV-Repair (http://groups.yahoo.com/group/tv-repair)
Monitor-Repair (http://groups.yahoo.com/group/monitor-repair)

----- Original Message -----
From: "Harvey Altstadter hrconsult@... [Homebrew_PCBs]"
<Homebrew_PCBs@yahoogroups.com>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, July 04, 2017 12:40 AM
Subject: Re: [Homebrew_PCBs] Ferric chloride staining PCB substrate


> Steve,
>
> With regard to dissolving epoxy, I have good news, and I have bad news.
> The good news is that there are chemicals used for depotting
> encapsulated assemblies.
>
> Back in the days before dirt was invented, I ran a failure analysis lab
> for my employer where my technicians used several chemicals from
> Dynaloy. They were sold under the Dynasolve product line. We also used
> another product of theirs called Decap. Here is a website for one of
> their distributors: http://www.ellsworthadhesives.ca/manufacturer/dynaloy
>
> I note that they now have a greater variety of chemicals than were
> available "way back then."
>
> That being said, there are a few issues (the bad news):
>
> 1. The chemicals don't dissolve the epoxy. They swell the epoxy and
> cause it to flake off. Active removal (scraping) is required
>
> 2. I think we had to match the chemical to the epoxy cure system, i.e.
> amine, phenol, etc., to get the best performance. I don't know if this
> is more or less so now, with the greater number of chemicals available
> today.
>
> 3. Since the circuit boards are usually epoxy impregnated, they will
> suffer as a result of this treatment. Any other parts that are epoxy
> encapsulated, or made with certain plastics would likely be adversely
> affected.
>
> 4. To say that the chemicals were pricey, would be a gross
> understatement. We bought them by the gallon, and each gallon cost an
> arm, a leg, and someone's first born son.
>
> The chemicals did the job for us because our usual need was to retrieve
> the failed components from the assembly. We had little concern for the
> assembly itself. The items we were after were in metal or ceramic
> packages, and therefore were not affected by the chemicals. Although the
> possibility of removing the epoxy and repairing an assembly exists, it
> is expensive and labor intensive, with a low probability of success.
>
> On the very rare occasion that a module had to be repaired because there
> was no other choice, a different technique was used. This technique is
> not generally available outside a lab like ours, but I present it just
> in case you have access to the necessary machinery/information.
>
> This technique requires good information on the construction of the
> module. We started by performing X-Ray in X, Y and Z axes. The X-Ray
> results were compared to the original assembly drawings, and the
> component of interest was located. By using extremely precise drilling
> and milling tools, combined with progressive X-Rays, a cavity was made
> around the part to be replaced. Every attempt was made to make the
> cavity very close to the part. The cavity was then filled with the
> chemical of choice, and the epoxy slowly scraped away, exposing the
> component. Just watching this process was painful. I don't even want to
> discuss how difficult it was to replace a component once the cavity was
> open and the defective component removed. To underscore: this was only
> done when there was no possibility of getting a replacement module, or
> the time it would take to get a replacement would have a devastating
> impact on delivery schedule.
>
> Harvey A
>
> On 7/3/2017 11:57 AM, 'Technotronic~Dimensions'
> infotech@... [Homebrew_PCBs] wrote:
>>
>> Hi
>>
>> Sorta new here and trying to catch on to some of the procedures described
>> here.
>>
>> Was wondering if anyone knows if theres a chemical or chemicals (s) that
>> will safely dissolve epoxy that some manufacturers
>> use to encapsulate boards to protect them and make them more or less
>> unservicable when a component fails?
>>
>> I have hears there is a chemical that they can be soaked in for many
>> days,
>> and you have to check on it daily before it eats through
>> things that u dont want it to damage.
>>
>> Steve Hearns
>> Technotronic Dimensions [USA]
>> WWW.TECHNOTRONIC-DIMENSIONS.COM
>> 1.518.663.3421 (MAIN)
>> 1-877-817-9885 (Voice / Fax Toll Free - US Only)
>> E-Mail: Steve@...
>> --
>> Webmaster, Parts-Link: (http://www.parts-link.com)
>> Group Moderator:
>> TV-Repair (http://groups.yahoo.com/group/tv-repair)
>> Monitor-Repair (http://groups.yahoo.com/group/monitor-repair)
>>
>> ----- Original Message -----
>> From: "LEON HELLER leon355@... [Homebrew_PCBs]"
>> <Homebrew_PCBs@yahoogroups.com>
>> To: <Homebrew_PCBs@yahoogroups.com>
>> Sent: Monday, July 03, 2017 12:56 AM
>> Subject: Re: [Homebrew_PCBs] Ferric chloride staining PCB substrate
>>
>> Oxalic acid removes ferric chloride stains. I've got a big bottle of it
>> somewhere but have never used it.
>> Leon
>>
>> On Monday, 3 July 2017, 2:56, "'Brad' unclefalter@...
>> [Homebrew_PCBs]" <Homebrew_PCBs@yahoogroups.com> wrote:
>>
>>
>
>

Steve,

I didn't want to mention MEK. This is bad stuff. Our company used it in the shop to clean up epoxy spills and the like. A respirator or aggressive ventilation system is a must. It is highly flammable, and is directly absorbed through the skin. Apparently, it is a neurotoxin. Definitely something to stay away from.

 

Hi Harvey

Great info, thanks. With more stuff out there being designed not to be
fixed, and thrown away, I had always wanted to
know more about the possibilities.

I remember when I worked in the Aerospace industry, the painter at our plant
carried MEK / Methyl Ethyl Keotene
around in ample supply, and some of that on a cloth woould pretty much take
the paint right off the surface of an
airplane no problem.

I remember it was not very pleasant at all to smell and it had a pretty high
hazmat rating sticker on it and he did not
leave that container open unless he was using it. He was suppose to wear a
respirator also if I remember right.

I got the impression that stuff would dissolve most anything even maybe
tough epoxy but never tried it.

Steve Hearns
Technotronic Dimensions, VT [USA]
WWW.TECHNOTRONIC-DIMENSIONS.COM
1.518.663.3421 (MAIN)
1-877-817-9885 (Voice / Fax Toll Free - US Only)
E-Mail: Steve@...
--
Webmaster, Parts-Link: (http://www.parts-link.com)
Group Moderator:
TV-Repair (http://groups.yahoo.com/group/tv-repair)
Monitor-Repair (http://groups.yahoo.com/group/monitor-repair)

----- Original Message -----
From: "Harvey Altstadter hrconsult@... [Homebrew_PCBs]"
<Homebrew_PCBs@yahoogroups.com>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Tuesday, July 04, 2017 12:40 AM
Subject: Re: [Homebrew_PCBs] Ferric chloride staining PCB substrate

> Steve,
>
> With regard to dissolving epoxy, I have good news, and I have bad news.
> The good news is that there are chemicals used for depotting
> encapsulated assemblies.
>
> Back in the days before dirt was invented, I ran a failure analysis lab
> for my employer where my technicians used several chemicals from
> Dynaloy. They were sold under the Dynasolve product line. We also used
> another product of theirs called Decap. Here is a website for one of
> their distributors: http://www.ellsworthadhesives.ca/manufacturer/dynaloy
>
> I note that they now have a greater variety of chemicals than were
> available "way back then."
>
> That being said, there are a few issues (the bad news):
>
> 1. The chemicals don't dissolve the epoxy. They swell the epoxy and
> cause it to flake off. Active removal (scraping) is required
>
> 2. I think we had to match the chemical to the epoxy cure system, i.e.
> amine, phenol, etc., to get the best performance. I don't know if this
> is more or less so now, with the greater number of chemicals available
> today.
>
> 3. Since the circuit boards are usually epoxy impregnated, they will
> suffer as a result of this treatment. Any other parts that are epoxy
> encapsulated, or made with certain plastics would likely be adversely
> affected.
>
> 4. To say that the chemicals were pricey, would be a gross
> understatement. We bought them by the gallon, and each gallon cost an
> arm, a leg, and someone's first born son.
>
> The chemicals did the job for us because our usual need was to retrieve
> the failed components from the assembly. We had little concern for the
> assembly itself. The items we were after were in metal or ceramic
> packages, and therefore were not affected by the chemicals. Although the
> possibility of removing the epoxy and repairing an assembly exists, it
> is expensive and labor intensive, with a low probability of success.
>
> On the very rare occasion that a module had to be repaired because there
> was no other choice, a different technique was used. This technique is
> not generally available outside a lab like ours, but I present it just
> in case you have access to the necessary machinery/information.
>
> This technique requires good information on the construction of the
> module. We started by performing X-Ray in X, Y and Z axes. The X-Ray
> results were compared to the original assembly drawings, and the
> component of interest was located. By using extremely precise drilling
> and milling tools, combined with progressive X-Rays, a cavity was made
> around the part to be replaced. Every attempt was made to make the
> cavity very close to the part. The cavity was then filled with the
> chemical of choice, and the epoxy slowly scraped away, exposing the
> component. Just watching this process was painful. I don't even want to
> discuss how difficult it was to replace a component once the cavity was
> open and the defective component removed. To underscore: this was only
> done when there was no possibility of getting a replacement module, or
> the time it would take to get a replacement would have a devastating
> impact on delivery schedule.
>
> Harvey A
>
> On 7/3/2017 11:57 AM, 'Technotronic~Dimensions'
> infotech@... [Homebrew_PCBs] wrote:
>>
>> Hi
>>
>> Sorta new here and trying to catch on to some of the procedures described
>> here.
>>
>> Was wondering if anyone knows if theres a chemical or chemicals (s) that
>> will safely dissolve epoxy that some manufacturers
>> use to encapsulate boards to protect them and make them more or less
>> unservicable when a component fails?
>>
>> I have hears there is a chemical that they can be soaked in for many
>> days,
>> and you have to check on it daily before it eats through
>> things that u dont want it to damage.
>>
>> Steve Hearns
>> Technotronic Dimensions [USA]
>> WWW.TECHNOTRONIC-DIMENSIONS.COM
>> 1.518.663.3421 (MAIN)
>> 1-877-817-9885 (Voice / Fax Toll Free - US Only)
>> E-Mail: Steve@...
>> --
>> Webmaster, Parts-Link: (http://www.parts-link.com)
>> Group Moderator:
>> TV-Repair (http://groups.yahoo.com/group/tv-repair)
>> Monitor-Repair (http://groups.yahoo.com/group/monitor-repair)
>>
>> ----- Original Message -----
>> From: "LEON HELLER leon355@... [Homebrew_PCBs]"
>> <Homebrew_PCBs@yahoogroups.com>
>> To: <Homebrew_PCBs@yahoogroups.com>
>> Sent: Monday, July 03, 2017 12:56 AM
>> Subject: Re: [Homebrew_PCBs] Ferric chloride staining PCB substrate
>>
>> Oxalic acid removes ferric chloride stains. I've got a big bottle of it
>> somewhere but have never used it.
>> Leon
>>
>> On Monday, 3 July 2017, 2:56, "'Brad' unclefalter@...
>> [Homebrew_PCBs]" <Homebrew_PCBs@yahoogroups.com> wrote:
>>
>>
>
>

Or just gho into the garden and pick some Rhubarb leaves, lots of Oxalic acid in them. Just don't eat any or drink what you make from boiling them or the grass will be growing green over your prostrate form.

Malcolm

I don't suffer from insanity I enjoy it!
Mene, mene, tekel, upharsin
The writing is on the wall.
Ha-ktovet al ha-kir

--------------------------------------------

On Tue, 7/4/17, roylowenthal@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:

Subject: [Homebrew_PCBs] Re: Ferric chloride staining PCB substrate
To: Homebrew_PCBs@yahoogroups.com
Date: Tuesday, July 4, 2017, 3:20 AM


 









Oxalic acid is also sold as, "wood
bleach" usually findable in hardware or paint
stores.
Roy









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See:
<http://copperplumbing.org.uk/sites/default/files/content_attachments/guide-to-suitability-with-chemicals.pdf>

Oxalic acid is slow to attack copper, so rinse well after using it. It is very poisnous, use Nitrile gloves and eye protection. Look up the MSDS on using it. You are unlikely to want a strong solotution, but take precautions.

Malcolm

I don't suffer from insanity I enjoy it!
Mene, mene, tekel, upharsin
The writing is on the wall.
Ha-ktovet al ha-kir

--------------------------------------------

On Tue, 7/4/17, 'Brad' unclefalter@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:

Subject: RE: [Homebrew_PCBs] Re: Ferric chloride staining PCB substrate
To: Homebrew_PCBs@yahoogroups.com
Date: Tuesday, July 4, 2017, 5:36 PM


 









Thanks!!  Question – will Oxalic eat at
the copper traces if I’ve removed the resist already?  I
haven’t on one board but the other I have.  From: Homebrew_PCBs@yahoogroups.com
[mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Tuesday, July 4, 2017 6:03 AM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Re: Ferric
chloride staining PCB substrate    Or just gho into the garden
and pick some Rhubarb leaves, lots of Oxalic acid in them.
Just don't eat any or drink what you make from boiling
them or the grass will be growing green over your prostrate
form.

Malcolm

I don't suffer from
insanity I enjoy it!
Mene, mene, tekel,
upharsin
The writing is on the wall.
Ha-ktovet al ha-kir

--------------------------------------------
On Tue, 7/4/17, roylowenthal@...
[Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com>
wrote:

Subject:
[Homebrew_PCBs] Re: Ferric chloride staining PCB
substrate
To: Homebrew_PCBs@yahoogroups.com
Date: Tuesday, July 4, 2017, 3:20 AM


 









Oxalic acid is also sold as, "wood
bleach" usually findable in hardware or
paint
stores.
Roy









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 Virus-free. www.avg.com

 









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